Pre-operative preparation with topical antimicrobial agent is an important step to reduce infection in surgical wounds. It is accepted medical practice to apply a topical antimicrobial agent to a surgical site or to a needle entry site to reduce the infection rate. Such treatment helps to control the growth of microorganisms in a wound, a surgical incision, or a needle puncture site. Topical antimicrobial agents are also known in the art as skin-preparations when used to prepare human skin for surgical procedures. The term skin-preparation is used herein to generally describe the class of topical antimicrobial agent solutions.
The application of skin-preparations is known in the art. Such skin-preparations have been applied in the form of preoperative skin treatments. Generally, the skin-preparations contain a broad spectrum antimicrobial agent. Iodine and chlorhexidine are well known broad spectrum antimicrobial agents. Skin preparations containing iodine in combination with polymers are also generally known as iodophor skin-preparations. Existing iodophor skin-preparations typically include an iodine-polymer complex, iodide, a surfactant and a buffer system to provide an appropriate pH in an aqueous system. The iodophor skin-preparations will typically contain 7.5% to 10.0%, on a volume per volume ("v/v") basis, of an iodine-polyvinyl pyrrolidone complex. The iodine-polyvinyl pyrrolidone complex is also known as PVP-I. These concentrations of PVP-I are desirable to provide effective and extended killing of microorganisms.
Standard surgical procedures require the surgical site to be disinfected prior to surgery. Effective pre-operative cleansing of the surgical site is critical to reducing the risk of infection to the patient. Pre-operative skin preparation is therefore as important as a prophylactic antibiotic treatment is in control of infection.
Microorganisms on the skin can be transient or resident. Transient microorganisms lie on the surface of the skin, while resident microorganisms are found at deeper sites in the skin, for example, in skin hair follicles. It is desirable to kill microorganisms both at the skin surface and at sites deeper in the skin. It is also desirable to provide both an initial quick kill and retain a long-term residual antimicrobial activity. It is important that the antimicrobial activity be sustained throughout a surgical procedure by a single application of the skin-preparation.
The conventional method of application of a skin-preparation is to pour a skin-preparation of 7.5% v/v PVP-I scrub solution into a tray, saturate a sponge with the skin-preparation in the tray and then apply the saturated sponge to the surface of skin. The skin-preparation is applied from the center to the peripheral areas of the skin site with a circular scrubbing motion for two to five (2-5) minutes. The sponge provides a physical force to spread the skin-preparation evenly and to remove dead skin cells and skin debris thus delivering the skin-preparation to exposed microorganisms. The site is then blotted dry and painted with a 10% v/v PVP-I solution.
Film forming skin-preparations, such as liquids that form a film after evaporation, are also known in the art. One film forming skin-preparation includes acrylic polymers and iodine complexed with polyvinyl pyrrolidone. Alternatively, a polyvinyl pyrrolidone vinyl acetate copolymer with diisocyanate has been used where iodine is complexed with the polyvinyl pyrrolidone component. Another film forming skin-preparation has been made employing a copolymer of the acrylic or methacrylic acid ester of an alkyl alcohol containing a single hydroxyl group with an N-vinyl lactam. In this latter composition, a broad spectrum antimicrobial agent is complexed with the N-vinyl lactam.
Other compositions providing film forming skin-preparations have been tried. One such composition is the reaction product of an isocyanate prepolymer with polyvinyl pyrrolidone, where a chain extender for the two monomers is employed and iodine is complexed to the polyvinyl pyrrolidone portion of the reaction product. Yet another example is an acetalized polyvinyl alcohol which has been complexed with iodine.
Each of the prior art compositions has disadvantages. Many of the prior art skin-preparations are water soluble. Therefore, such topical agents are removed when a wound or surgical site is irrigated during surgery. Some of the prior art skin-preparations are water insoluble and can only be removed by an organic solvent. Therefore, to remove such skin-preparations requires the application of alcohol, for example, to an already tender wound or surgical site.
It would therefore be advantageous to have a skin-preparation which is resistant to water when dry so that it is not removed when a wound or surgical site is sponged or irrigated. It would also be an advantage to have a skin-preparation which may be removed from the wound or surgical site without resorting to the application of an organic solvent such as alcohol. It would be yet a further advantage to have a skin-preparation that presents the above listed advantages and has an efficacy similar to that for water soluble skin-preparations.